== AMQP Message Queue ==

=== Invoice Lifecycle ===

  # System 36 generates invoice and "prints" it
  # Redmon intercepts that data by acting like a printer
  # Custom C# tool RawUploader writes this data to a local database
  # Custom C# tool DataQueueDispatcher uploads records from local database to CRM Printlog Raw table
  # CRM takes Raw record and parses it into a CRM Invoice record
  # CRM submits Invoice id and formats to be printed to AMQP message queue to be printed
  # Custom C# tool PrintDaemon monitors AMQP message queue and spools any waiting records to the selected printer

We use a message queue, RabbitMQ, to store invoices waiting to be printed. The RabbitMQ daemon runs on Server20081 and publishes a queue called invoice. Print tools and the CRM interface with this queue with the credentials stored in KeePass.

=== Clear the Queue ===

In the case of certain errors the message queue may need to be cleared. You can do that by logging into the AMQP server and issuing the following command.

**Note:** <wrap hi>Only unacknowledged messages can be cleared. So any queue monitoring programs should be stopped.</wrap>
<code>
rabbitmqctl purge_queue <queue_name>
</code>

You can be sure the command worked by checking the queue status.
<code>
rabbitmqctl list_queues
</code>